Cardiovascular disease (CVD) remains the leading cause of death in the United States. A large body of evidence supports a causal role for oxidative stress in various forms of CVD, especially myocardial ischemia- reperfusion injury. As such, exogenous antioxidant compounds have been used for intervention of CVD. However, clinical trials on use of exogenous antioxidants, including vitamin E in management of CVD have reached disappointing conclusions. It is increasingly recognized that the coordinated actions of various endogenous antioxidant enzymes are essential for efficient detoxification of ROS and other reactive species that mediate cardiac injury. Accordingly, we propose a novel strategy for myocardial salvage from ischemia- reperfusion injury via enhancing the coordinated expression of the endogenous antioxidant network in myocardium. The long-term objective of this project is to develop a highly effective endogenous antioxidant- based cardioprotective strategy to prevent and/or retard the oxidative degenerative processes underlying cardiac disease. Such a strategy of myocardial salvage relies on a profound understanding of molecular regulation of constitutive and inducible expression of cardiac antioxidant network. Recently, Nrf2 is found to be a central regulator of cytoprotective gene expression in animal tissues, including liver and lung. However, the role of Nrf2 in regulating antioxidant network in myocardium remains to be determined. We hypothesize that Nrf2 is indispensable for regulating coordinated expression of antioxidant enzymes in myocardium, and that the Nrf2-regulated cardiac antioxidant network is a novel pathway for myocardial salvage from ischemia- reperfusion injury. Accordingly, this R21 proposal aims to identify the essential role of Nrf2 in regulating coordinated expression of myocardial antioxidants and the signaling pathways involved via using the novel Nrf2-knockout mouse model. The potent chemoprotective agent, 3H-1,2-dithiole-3-thione (D3T) will be used to define the central role of Nrf2 in regulating the inducible expression of myocardial antioxidants and the underlying mechanisms. This proposal will also be aimed to determine if Nrf2-dependent coordinated expression of cardiac antioxidants is a crucial mechanism for myocardial salvage from in vivo ischemia- reperfusion injury. Completion of this project will identify Nrf2 signaling as a novel pathway for mitigating myocardial ischemia-reperfusion injury, and significantly contribute to the development of a highly effective cardioprotective strategy via targeting on Nrf2-regulated antioxidant network in myocardium. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE Myocardial ischemia-reperfusion injury is a major clinical problem, for which there is no effective approach to intervention. Substantial evidence supports a causal role for reactive oxygen species (ROS) in the pathogenesis of myocardial ischemia-reperfusion injury. This project aims to identify Nrf2 signaling as a novel pathway for myocardial salvage from ischemia-reperfusion injury. Completion of this project will contribute to the development of a highly effective cardioprotective strategy via targeting on Nrf2-regulated antioxidant network for intervention of myocardial ischemia-reperfusion injury as well as other cardiac disorders that involve an ROS-mediated mechanism.